how to form2 open only once at time ?

private void button1_Click(object sender, EventArgs e)
{
Form2 myForm;
myForm = new Form2();
myForm.ShowDialog();
}

A better answer than all of these would be, read the answer you got to the last question, use the code you were given there, and once your form is a member variable, you can check if it's open and you can't create more than one, as you have one only that you work with, instead of creating a new one every time this method is called.

As you're obviously just playing, why not read some online articles or buy a book so you can learn this properly. There's major gaps in your knowledge that mean the fact you have two forms on the screen probably makes you think you know a lot more than you really do.

Hello,

I think it can help you:

public partial class Form1 : Form
{
    private Form form2;

    public Form1()
    {
        InitializeComponent();

        InitializeForm2();
    }

    private void InitializeForm2()
    {
        form2 = new Form(); //You can add some details
        //I prefer to have a ready form for example: ReadyForm
        //then:
        // form2 = ReadyForm();
        // Instead of form2 = new Form();
    }

    private void MyButton_Click(object sender, EventArgs e)
    {
        if (form2.IsAccessible)
            return;

        if (form2.IsDisposed)
            InitializeForm2();

        form2.Show();
    }

   //....

}

Declare

public static bool isOpen = false;

in Form2
set
and On PageLoad_Form2

isOpen = true;

Now on Button Click (that open Form2)

if (Form2.isOpen==false)
            {
  Form2 bc = new Form2();
   bc.Show();
               
            }

Hope It will solve your problem...

majid54787,

Try the following modification

private void button1_Click(object sender, EventArgs e)
{
Form2 myForm;
myForm = new Form2();
myForm.ShowDialog();
}

The .ShowDialog() will force the other form in front. Until that form is closed, there is nothing you can do on the parent form.

Hogan

What you need is a static boolean flag, like ifForm2Open, which you set to true in the constructor for Fform2 and set to false in the destructor.

Now, again in the instructor, you add code Form2.close() if ifForm2Open is true.


You can also make the flag publicly visible and use it to control the enable/disable from the parent window/class.

The static declaration exists because it is useful. Have you never used a static functions (usable without declaring the class?). They exist throughout the .NET namespaces. You probably use them without knowing it.
    Eg.   Convert:ToString(142);

A static member is visible through all instances of a class - and it's values is the same in ALL instances. That allows setting the flag when you open the first instance to be detectable when trying to open the second instance: you can then the second instance to not open. Similarly, when you finally close the first (and only) instance, it clears the flag.

RESTATED:
A static variable has a fixed memory location (in the heap rather then the stack). It persists so long as the program that contains the class is running. It therefore allows the transmission of information amongst the different instances of the class. As I noted, you could use an int (instead of a bool), and then keep track of how many instances are currently open.

Your
private bool form2isFlagged - will be useful how ? ? ? Withing the form it's only visible in the form: useless! If it's outside your class, you need to maintain it - what will be its scope?

private System.Windows.Forms.Form form2 will help you how? The form can be open or closed without being null, depending upon scope. When a form is closed, its pointer doesn't need to null - it wasn't null before the form was opened, either, once you declared an instance. Do you want to be sure if the window is open or ALMOST sure ? Hell of a program that would be.

Why a static symbol? Part of the form's class - and set up as I noted in my original post, take care of itself when it comes to instance count limits. If private, can't be monkeyed with outside the form class. Why wouldn't you want the class to do the work for you.

FURTHERMORE - if you are clever, clicking on the button that created Form2 could be used to move the existing instance to the top of the Z-order, giving the user the perception that the program is cooperating.

A lot of bang for the buck if you use static.

Try This

private void mnuYourForm(object sender, EventArgs e)
{
    if (IsFormAlreadyLoaded("YourFormName") == true)
    {
        return;
    }
}

Call This routine Before you open your form as shown above

private bool IsFormAlreadyLoaded(string formToLoadName)
 {
    foreach (Form frmChild in this.MdiChildren)
    {
        if (frmChild.Name == formToLoadName)
        { frmChild.Activate(); return true; }
    }
    return false;
 }

This Will Definitely work